After a battery of tests including chest x-rays, ultrasound scans and an MRI, Megan was given a clean bill of health.

It was then that a tumour was found on Sophie's kidney.

She was the one who was sick all along.

"It was heartbreaking," the 37-year-old mum said. "There was no indication anything was wrong with Sophie."

Sophia's kidney cancer is called a Wilms' tumour and it is the most common type of kidney cancer that affects children in Australia, and approximately 70 children in the UK each year.

Megan has been an incredible support to her identical twin sister during her cancer battle, and thankfully Sophie is expected to make a full recovery, although she will be watched closely for the rest of her life.

(Just Giving)

Sophie has lost her hair, and despite Megan wanting to cut her hair in solidarity with her identical twin sister, their mum can bring herself to let her do it.

"Megan is my reminder of how Sophie looked and hopefully will look again soon," she said.

Sophie has undergone surgery to remove the tumour as well as her left kidney in December in a seven-hour operation. She will undergo chemotherapy until June.

The 11-year-old is being fed through a tube in her nose.

Rebecca says the twins are closer than ever before.

"Now Megan wants to be with Sophie more than ever. I don't know what she would do without her."